About algae

About algae

Algae is a natural part of the aquatic ecosystem with most species safe or non-toxic. However, some algae can produce toxins that can be damaging to humans, domestic animals and livestock that drink or come in contact with the water, and also organisms living in water. These algae can be found in freshwater as well as marine and estuarine waters.

Blue-green algae (also known as cyanobacteria) are the only group of algae known to be toxic in freshwaters. They are microscopic bacteria living in water, and are capable of photosynthesising which is why they are often called algae. Though microscopic, when they form colonies and accumulate together they can become visible to the naked eye. Blue–green algae can produce potent liver and neurotoxins as well as skin irritants. However, not all blue–green algae are toxic, and even toxic species do not always produce toxins.

Many blue-green algal species are able to regulate their buoyancy and can sometimes be seen as green scums on water, or they just colour the water green. See Key to Blooms for more information on identifying blooms.

Toxic marine and estuarine algae can also affect recreational water use. Some of these algae produce toxins that can cause illness, particularly if contaminated shellfish is ingested, and others can cause skin irritations. These algae often cannot be seen, but some cause red discolouration to water a phenomenon known as red–tides.

WaterNSW's role in algae management

  • Co-ordinate and support Regional Algal Co-ordinating Committees (RACCs)
  • Contributes to the State Algal Advisory Group (SAAG).
  • Contributes to the Regional Algal Management Guidelines.
  • Manages algal communications including hotline, media enquiries, website and briefings to Minister.
  • Monitors rivers and storages to service those aspects of the RACC’s reporting requirements, in accordance with the RACC Guidelines and WaterNSW Service Provision Deed.

WaterNSW's algae management actions

  • Take a lead role in managing the risk of algal blooms in fresh waters by coordinating algal monitoring, management and public information (media and web based information) in surface waterways and storages where no other management organisation has a role.
  • Liaise with other agencies affected by algal blooms in order that an integrated risk management approach is taken.
  • Perform a knowledge broker role and facilitate communication between regional stakeholders and the State body responsible for algal management
  • Identify knowledge gaps and encourage research to provide new information to enhance algal monitoring and management.
  • Co-ordinate and manage regular algal information on behalf of stakeholders and ensure that water users and other stakeholders are informed.


Tuesday 17 May
2,573,926 ML
2,581,850 ML
9,342 ML
1,335 ML
50,768 ML
Tuesday 17 May